In-situ alloying of AlSi10Mg+Si using Selective Laser Melting to control the coefficient of thermal expansion

Abstract

Selective Laser Melting (SLM) was investigated as new processing route for strongly hypereutectic AlSi alloys for thermal management applications in space industry. Processing conditions, microstructure and thermal expansion behavior were analyzed for AlSi10Mg+Si alloys with 25 wt% and 50 wt% Si fabricated by in-situ SLM of powder mixtures. For both Si compositions parts with densities ≥ 99% could be achieved using laser power ≥ 275 W and scan speeds ≥ 1500 mm/s for the alloy containing 25 wt% Si and laser power of 400 W and scan speeds ≥ 1500 mm/s for the alloy containing 50 wt% Si. Considerable refinement of primary and eutectic Si was achieved for both Si compositions due to the high cooling rates of SLM. The mean particle size for the coarse primary Si of the 50 wt% Si containing alloy was below 10 µm. Additionally, unmolten Si powder particles were observed. Measurements of the coefficient of thermal expansion (CTE) showed the tailorability of CTE with adjustment of Si content. A decrease in CTE of 43% compared to pure Al was achieved at a total Si content of 50 wt%. Experimental data was close to model calculations based on the rule of mixture and the Turner model depending on the different microstructures of the two alloy compositions.

Microstructure and Mechanical Properties of Hypereutectic Al-High Si Alloys up to 70 wt.% Si-Content Produced from Pre-Alloyed and Blended Powder via Laser Powder Bed Fusion

“…So, the findings in the literature about processibility via PBF–LB/M, and the material properties, are not consistent. On the one hand, several researchers reported cracks in AlSi40 [ 12 , 13 , 14 ] and AlSi50 samples [ 15 ]. On the other hand, other findings did not mention any crack formation [ 4 , 10 , 16 ].…”

Microstructure and Mechanical Properties of NiTi-Based Eutectic Shape Memory Alloy Produced via Selective Laser Melting In-Situ Alloying by Nb

“…However, the production of pre-alloyed powders is usually time and labor consuming, especially in the case of custom alloys. The use of an elemental powder blend in the SLM process is an alternative option that can be used for in-situ synthesis or in-situ alloying during the SLM process to obtain a material with a required composition [20][21][22]. At the same time, rapid solidification and cooling rates typical for the SLM process lead to insufficient diffusion of elements with high melting points, which causes a heterogeneous microstructure.…”

Synchrotron Characterisation of Ultra-Fine Grain TiB2/Al-Cu Composite Fabricated by Laser Powder Bed Fusion

“…To meet the growing demand for lightweight components in the automotive and aerospace sectors, many researchers have used LPBF to fabricate high-performance aluminium (Al) alloys and composites. A variety of Alalloys have been successfully printed using LPBF, including Al-Si [4], Al-Si-Mg [5,6], Scalmalloy [7,8], Al-Mn-Sc [9,10], Al-Mg-Si-Sc [11,12], Al-Cu [13,14] and Al-matrix composites [15][16][17].…”